Hybrid stone retrieval device

ABSTRACT

Baskets with multiple portions and multiple deployed configurations allow the capture and release of material within the body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No.09/369,226, filed Aug. 6, 1999, and a continuation-in-part of U.S.patent application Ser. No. 08/968,906, filed Nov. 5, 1997, which is acontinuation of U.S. patent application Ser. No. 08/822,207, filed Mar.20, 1997, abandoned, which is a continuation of U.S. patent applicationSer. No. 08/382,778, filed Feb. 2, 1995, abandoned. The entirety of eachof the applications is incorporated by reference herein.

TECHNICAL FIELD

This invention generally relates to medical instruments such asretrieval devices for retrieving material from within a body. Moreparticularly, the invention relates to retrieval devices for capturingand releasing stones such as urinary tract stones, gall stones, andother biological materials from a body tract.

BACKGROUND INFORMATION

Medical retrieval devices generally are used to retrieve biological andforeign material including stones from the body. Such medical retrievaldevices may be used through an endoscope or a laparoscope.

One type of known medical retrieval device has a sheath and a retrievalassembly such as a basket that is movable in and out of the sheath. Whenthe basket is within the sheath, the basket assumes a collapsed, reduceddiameter profile. When the sheath is retracted relative to the basket orthe basket is moved beyond the end of the sheath, the basket expands toa relatively larger diameter than when the basket is enclosed within thesheath. Generally, the contour of known baskets is round or oval and isformed by a plurality of legs.

With many known retrieval devices, materials are used in the retrievalassembly to enhance its rigidity. However, rigid materials used toenhance strength do so at the expense of flexibility. The retrievalassembly must, on the one hand, be sufficiently strong to dilate thebody tract and, on the other hand, be sufficiently flexible to negotiatebody tracts having small diameters, tortuous pathways and irregularlumens. Moreover, flexible retrieval assemblies can more easily capturelarge stones through the gaps in the legs of the retrieval assembly,than can rigid retrieval assemblies. When flexible materials are used inthe retrieval assembly, however, rigidity and strength are compromised.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a medical instrument, i.e.,a medical retrieval device with features that permit retrieval ofmaterial within a body. The material can be biological material, such asstones, or foreign material, or any of a variety of other types ofmaterial within a body. The material can be located in a urinary orbiliary tract or elsewhere in the body.

A medical instrument according to the invention is used to treat aninternal organ which includes material such as a calculus or athromboembolus. The medical instrument typically includes a proximalhandle, a sheath extending from the handle and including a lumen and adistal end away from the handle, and a retrieval assembly such as abasket.

The retrieval assembly has a proximal portion and a distal portion. Theproximal portion is made with a first material and the distal portion ismade with a second different material.

The retrieval assembly and the sheath are moveable relative to eachother to achieve a collapsed position of the retrieval assembly in whichthe retrieval assembly is within the lumen of the sheath and anotherposition of the retrieval assembly in which at least a portion of theretrieval assembly extends from the distal end of the sheath. In thisposition, the retrieval assembly assumes a three-dimensional shape outof the lumen of the sheath.

In one embodiment, the retrieval assembly is a basket. The basket has aplurality of legs, for example, the basket has three, four, five or morelegs. The legs may be preformed.

In one embodiment of the invention, the legs of the retrieval assemblyfeature a proximal and a distal portion. The proximal portion of thelegs comprises a first material and the distal portion of the legscomprises a second material, the second material being more flexiblethan the first material. In this embodiment, the proximal leg portionand the distal leg portion are connected at a joint. The joint is aloop, hook, crimp, solder, weld, or any other mechanism known forconnecting the ends of at least two wires or legs.

In another embodiment of the medical retrieval device of the invention,the proximal portion of the retrieval assembly is generally straight;the contour of the proximal portion being planar rather than curved.Alternatively, at least the proximal portion of the retrieval assemblyis bulbous, i.e., the proximal portion is bowed out from the center ofthe retrieval device when the proximal portion is deployed beyond thedistal end of the sheath.

Other embodiments of this invention include a sheath axially moveablerelative to the retrieval assembly. In this embodiment, retraction ofthe sheath in a direction away from the distal end of the sheath extendsthe retrieval assembly from the distal end of the sheath. The portionsof the retrieval assembly are thereby expanded depending on whichportions are uncovered by the retracted sheath.

Some additional embodiments of the invention include an elongated guidemember longitudinally positioned in the lumen of the sheath, operablyattached to a proximal end of the retrieval assembly, and actuated by atleast one actuating member on the handle. Reciprocal axial movement ofthe elongated guide member moves the retrieval assembly from itsenclosed position within the sheath, in and out of the distal end of thesheath and back to its enclosed position within the sheath. As theassembly is moved in and out the sheath, the portions of the retrievalassembly shift between collapsed and opened positions.

In yet another aspect, the invention relates to a method for retrievingmaterial from a body. The method comprises inserting a medical retrievaldevice with a retrieval assembly (such as the instrument describedabove) into a body, extending the proximal and distal portions of theretrieval assembly beyond the end of the sheath, maneuvering theretrieval assembly around the material, capturing the material withinthe retrieval assembly, withdrawing the proximal and distal portions ofthe retrieval assembly back into the sheath, and removing the medicalinstrument and the material captured in the retrieval assembly from thebody.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention.

FIG. 1 is a plan view of an embodiment of a medical retrieval deviceaccording to the invention.

FIG. 2 illustrates an embodiment of a retrieval assembly, according tothe invention, extended beyond the distal end of the sheath and open.

FIG. 3. illustrates the retrieval assembly illustrated in FIG. 2 withthe distal portion of the retrieval assembly extended beyond the distalend of the sheath and open.

FIG. 4A illustrates the retrieval assembly illustrated in FIG. 2collapsed within the distal portion of the sheath.

FIG. 4B illustrates an embodiment of a retrieval assembly according tothe invention.

FIG. 5A illustrates a front view of an embodiment of a joint between aproximal leg portion and a distal leg portion according to theinvention.

FIG. 5B illustrates a side view of the joint illustrated in FIG. 5A.

FIG. 6A illustrates a side view of an embodiment of a joint between aproximal leg portion and a distal leg portion according to theinvention.

FIG. 6B illustrates a front view of the joint illustrated in FIG. 6A.

FIG. 7A illustrates a front view of an embodiment of a joint between aproximal leg portion and a distal leg portion according to theinvention.

FIG. 7B illustrates a side view of the joint illustrated in FIG. 7A.

FIG. 8A illustrates a side view of a joint between a proximal legportion and a distal leg portion according to the invention.

FIG. 8B illustrates a front view of the joint illustrated in FIG. 8A.

FIG. 9 illustrates an embodiment of a retrieval assembly according tothe invention.

FIG. 10A illustrates an embodiment of a distal portion of a leg of aretrieval assembly according to the invention.

FIG. 10B illustrates an embodiment of a distal portion of two legs of aretrieval assembly according to the invention.

FIG. 10C illustrates an embodiment of a retrieval assembly including thelegs illustrated in FIG. 10B.

FIG. 11 illustrates an embodiment of a retrieval assembly according tothe invention.

FIG. 12A illustrates an embodiment of a retrieval assembly according tothe invention with the distal portion of the retrieval assembly extendedfrom the distal end of the sheath.

FIG. 12B illustrates the retrieval assembly in FIG. 12A with theproximal and distal portions of the retrieval assembly extended beyondthe distal end of the sheath.

FIG. 13 illustrates a perspective view of another embodiment of theretrieval assembly according to the invention.

FIG. 14 illustrates another embodiment of a retrieval assembly accordingto the invention.

FIG. 15 illustrates another embodiment of a retrieval assembly accordingto the invention.

FIG. 16 illustrates another embodiment of a retrieval assembly accordingto the invention.

FIG. 17 illustrates another embodiment of a retrieval assembly accordingto the invention.

FIG. 18A illustrates another embodiment of a medical retrieval deviceaccording to the invention.

FIG. 18B illustrates an end view of an embodiment of the retrievalassembly illustrated in FIG. 18A.

FIG. 18C illustrates an end view of another embodiment of the retrievalassembly illustrated in FIG. 18A.

FIG. 18D illustrates another embodiment of the retrieval assemblyillustrated in FIG. 18A.

FIG. 18E illustrates the retrieval assembly illustrated in FIB 18Dapproaching a stone.

FIG. 18F illustrates the retrieval assembly illustrated in FIB 18Dpartially collapsed around a stone.

FIG. 18G illustrates the retrieval assembly illustrated in FIG. 18Dcollapsed around a stone and partially collapsed within the distal endof the sheath.

FIG. 19A illustrates another embodiment of a retrieval assemblyaccording to the invention.

FIG. 19B illustrates another embodiment of a retrieval assemblyaccording to the invention.

FIG. 20A illustrates the retrieval assembly illustrated in FIG. 19Acollapsed within the sheath.

FIG. 20B illustrates the retrieval assembly illustrated in FIG. 20Aextended from the distal end of the sheath and open.

FIG. 20C illustrates a stone captured in the retrieval assemblyillustrated in FIG. 20B.

FIG. 21A illustrates the retrieval assembly illustrated in FIG. 19Bcollapsed within the sheath.

FIG. 21B illustrates the retrieval assembly illustrated in FIG. 21Aextended from the distal end of the sheath and open.

FIG. 21C illustrates a stone captured in the retrieval assemblyillustrated in FIG. 21B.

FIG. 22A illustrates another embodiment of the retrieval assemblyillustrated in FIG. 19A.

FIG. 22B illustrates another embodiment of the retrieval assemblyillustrated in FIB. 19B.

DESCRIPTION

Each of the following embodiments of a medical retrieval deviceaccording to the invention have at least the following properties. Theretrieval assembly of the medical retrieval device is made from a rigidmaterial and a flexible material. The proximal portion of the retrievalassembly is made with materials that are rigid relative to the materialsused in the other parts of the retrieval assembly. The materials used inthe portions of the retrieval assembly other than the proximal portionenhance flexibility of those portions relative to the flexibility of theproximal portion of the retrieval assembly.

In general, in one aspect, the invention features a medical retrievaldevice including a handle, a sheath, and a retrieval assembly. Asillustrated in FIG. 1, a medical retrieval device 1.0 includes a handle11 at a proximal end 12 having a handle base 13 and an actuatingmechanism 14, such as a slider. A physician can grasp the handle base 13in the palm of his or her hand and manipulate the actuating mechanism 14with his or her thumb. A retrieval assembly 15 formed in accordance withthis invention is located at the distal end 16 (end furthest fromoperator) of the medical retrieval device 10. The retrieval assembly 15,according to the invention, may have a number of different embodiments,one of which is illustrated in FIG. 1, and will be discussed in greaterdetail below. A sheath 17 overlies an intermediate supporting structure,such as an elongated member 40, between the handle 11 and the retrievalassembly 15. The sheath 17 typically comprises a polyimide tube or atube made from other materials that exhibit radial flexibility, axialstiffness, and biocompatibility.

The outside diameter of the sheath 17 can range from 1.7-8.0 French(Fr.). preferably 3.0 Fr. The retrieval assembly 15 is the type that canbe collapsed within a sheath 17 for entry into the body. The handle 11,sheath 17, and retrieval assembly 15 illustrated in FIG. 1 are not shownin their correct size or proportion to each other. The size of theentire sheath is dimensioned to fit the requirements of the applicationof the sheath 17 in the body. For example, for urological applications,the size of the device is typically 1.7-8.0 Fr. The sheath 17 has atleast one lumen 9 therein, may be made from a single material, andextends from the handle 11 to a distal sheath end 18. An elongatedmember 40 such as a cable, coil, shaft, guidewire or mandril wireextends within the lumen 9 from the device handle 11 to the base 30 ofthe retrieval assembly 15, where the elongated member 40 is attached atits distal end to the retrieval assembly 15.

The elongated member 40 is operably joined to one or more actuatingmechanisms 14 at the device handle 11. Referring to FIG. 1, when theactuating mechanism 14 is located at position 14 c, retrieval assembly15 is extended beyond the distal end 18 of the sheath 17 and completelyopen as illustrated in FIG. 2. As the actuating mechanism 14 is moved toposition 14 b, the retrieval assembly 15 moves to the position depictedin FIG. 3. When the actuating mechanism 14 is moved to position 14 a,the retrieval assembly is compacted by sheath 17 which covers theretrieval assembly 15 within the lumen 9 of the sheath 17 as depicted inFIG. 4A.

Alternatively, in another embodiment, the mechanism 14 can causemovement of the sheath 17 to advance the sheath 17 over the stationaryretrieval assembly 15 and elongated member 40 combination, to therebycollapse the retrieval assembly 15 within the sheath 17. In thisembodiment, as shown in FIG. 1, as the actuating mechanism advances fromproximal position 14 a to intermediate position 14 b as depicted inphantom, the sheath 17 advances from the position depicted in FIG. 2 tothe position shown in FIG. 3. As the actuating mechanism is advancedfurther to position 14 c, the sheath 17 compacts and covers theretrieval assembly 15 as shown in FIG. 4A.

In general, both types of retrieval assembly/sheath movementconfigurations and related handle mechanisms are known, and can be seenin existing product designs available from, for example, BostonScientific Corporation (Natick, Mass.). With the retrieval assembly 15collapsed within the sheath 17 as shown in FIG. 4A, the sheath 17 can beinserted into the body by an operator to a site in the body where thematerial to be retrieved is located (e.g., a stone in the ureter). Byplacing the retrieval assembly 15 into its open/expanded position, asillustrated in FIG. 2, the retrieval assembly 15 dilates the body tractin which it has been placed and can be manipulated by the operator toentrap or capture material within the retrieval assembly 15.

In general, in one aspect, referring to FIG. 2, the retrieval assembly15 is a basket formed by a plurality of legs 21. The number of legs canbe as many as 2-20. In this aspect of the invention, the retrievalassembly 15 is divisible into multiple basket portions such as aproximal basket portion 22 and a distal basket portion 24. The legs 21of the basket also have a proximal leg portion 26 and a distal legportion 28. The proximal leg portion 26 is located within the proximalbasket portion 22 and the distal leg portion 28 is located within thedistal basket portion 24. The proximal end of the proximal leg portion26 is joined to the elongated member 40 axially disposed within thelumen 9 of the sheath 17.

In general, the proximal leg portion 26 and the distal leg portion 28 ofeach leg 21 are made with different materials. The proximal leg portion26 is formed with a first material that is more rigid than the secondmaterial used in the distal leg portion 28. For example, the proximalleg portion 26 is formed with stainless steel and the distal leg portion28 is formed with Nitinol silk, nylon, other shape memory materials suchas nickel-titanium, nickel-titanium-copper, and nickel-titanium-lead.Other combinations of material are also contemplated by the invention aslong as the strands of the proximal leg portion 26 are more rigid thanthe filaments of the distal leg portion 28.

A retrieval assembly that includes a rigid proximal portion and acomparatively flexible distal portion has the advantage of providingboth sufficient strength for dilating a body tract and sufficientflexibility for capturing a stone or other material within the bodytract. The strands of the proximal leg portion 26 facilitate the ease bywhich stones or other material are captured. The gaps between thestrands in the proximal basket portion 22, are comparatively wider thanthe gaps between the filaments in the distal basket portion 24.Moreover, the flexibility of the distal basket portion 24 permitscapture of stones with diameters greater than the width of the gapbetween the legs 21. The filaments of the distal leg portions 28 flex topermit large stones to pass through the gaps between the legs 21 in thedistal basket portion 24. After a stone is captured, the stone istrapped in the distal basket portion 24 of the retrieval assembly 15where the gaps between the filaments of the distal leg portions 28 arecomparatively narrow.

The flexible distal basket portion 24 of the retrieval assembly 15enhances the ease by which a stone is captured when the stone is locateddistal to the retrieval assembly 15 or lateral to the distal basketportion 24 of the retrieval assembly 15. While the rigid proximal basketportion 22 of the retrieval assembly 15 has the strength to dilate thebody tract, the flexible filaments of the distal basket portion 24 havethe flexibility to flex apart to enable capture of a stone through thegaps between the filaments. The stone may enter through the distalportion of the basket via the distal end 23 of the retrieval assembly orthrough the side of the distal basket portion 24 of the retrievalassembly 15. Compared to rigid retrieval assemblies, the flexible distalbasket portion 24 of the retrieval assembly 15 also minimizes trauma tothe body tract that might result when the retrieval device is expandedin a body tract.

The filaments in the distal leg portion 28 constitute separate wires, oralternatively, the filaments are made from one wire or more than onewire, that is attached to the distal end 32 of a strand in the proximalleg portion 26 that comprises solid, twisted or braided wire. The numberof filaments in the distal leg portion 28 attached to the distal end 32of a strand in the proximal leg portion 26 is at least one, andpreferably as many as 2-10.

Connection of the filaments at the proximal end 33 of the distal legportion 28 to the distal end 32 of the strands in the proximal legportion 26 at a joint 27 is accomplished by a number of means. Forexample, as illustrated in FIGS. 5A and 5B, the filaments at theproximal end 33 of the distal leg portion 28 are crimped to the distalend 32 of the strands in the proximal leg portion 26 at a joint 27, or,as illustrated in FIGS. 6A and 6B, two filaments in the distal legportion 28 are formed from a single wire that pass through a hole 34positioned at the distal end 32 of the strand in the proximal legportion 26. Alternatively, as illustrated in FIGS. 7A and 7B, and 8A and8B, one or more filaments in the distal leg portion 28 passes through apartially closed loop or hook 36 positioned at the distal end 32 of astrand in the proximal leg portion 26. Other mechanisms by which thefilaments at the proximal end 33 of the distal leg portion 28 are joinedto the strands include solder, weld, knot, or adhesive. The number offilaments in the distal leg portion 28 that are shown in FIGS. 5A and 5Bthrough FIGS. 8A and 8B are meant to be illustrative and are not limitedto only those embodiments shown. The ratio of strands to filaments isequal to, or less than one.

In a particular embodiment, referring to FIGS. 2, 9, and 14-17, theproximal leg portion 26 of a leg 21 of the retrieval assembly 15according to the invention, features a strand of material. The distalleg portion 28 of a leg 21 features a plurality of filaments that extenddistally from each of the strands of the proximal leg portion 26 to adistal end 23 of the retrieval assembly. In one embodiment, illustratedin FIG. 2, for example, the distal ends of the filaments in the distalleg portion 28 are bundled together in an end cap 25. The cap 25captures the distal ends of all the filaments of the distal leg portion28 in the cap 25, by swaging or by some other means to form a distal end23 of the basket 15.

In one embodiment, an individual strand of the proximal leg portion 26is prestressed or preformed. Consequently, without confinement by thesheath 17, the strands in the proximal portion 22 of the retrievalassembly 15 diverge from each other as they extend distally. Thefilaments of the distal leg portion 28 are preformed to follow astraight or helical path from the ends of the strands in the proximalleg portion 26 to converge at the distal end 23 of the retrievalassembly to thereby define the distal leg portion 28 of the basket 15.

While FIG. 4A illustrates the strands in the proximal leg portion 26extending essentially parallel to each other, it will be understood thatthe strands in the proximal leg portion 26 could be intertwined ortwisted while still retaining a compact cross-section.

The strands in the proximal leg portion 26 of the proximal portion 22 ofthe retrieval assembly 15 could be preformed or stressed to follow ahelical path between the base 30 of the retrieval assembly 15 and thedistal portion 24 of the retrieval assembly 15. Additionally, as shownin FIG. 4B, the strands in the proximal leg portion 26 could vary inlength to ease collapse of the retrieval assembly 15 in the sheath 17.With either of these constructions, the distal end 23 of the retrievalassembly 15 remains radially flexible and, by virtue of the sheath 17,axially stiff to facilitate placement of the retrieval device 10. Atleast one wire is used to make the filaments of the distal leg portion28 in the distal portion 24 of the retrieval assembly 15. For example,as illustrated in FIG. 9, one wire is used to make two filaments of thedistal leg portion 28. A section of the wire passes through joint 27 atthe distal end 32 of the strand of the proximal leg portion 26 in themanner illustrated in FIGS. 6A and 6B. Both ends of the one wire areattached to the distal end cap 25. The joint 27 may take any of theforms described above, such as a hole, hook, or crimp.

Alternatively, one wire is used to make three, four, or more filamentsof the distal leg portion 28. As shown in FIG. 10A, in a one wire, fourfilament embodiment, the one wire is passed multiple times between thejoint 27, and distal end 23 of the retrieval assembly 15. It is possibleto have any combination of wires to form the filaments, for example, atleast one wire forming at least two filaments, and two additional wiresforming two additional filaments, all four filaments extending from thedistal end 32 of a single strand to form the distal leg portion 28 of asingle leg 21.

In another embodiment, illustrated in FIG. 10B, the same wire may beused for filament 28 a of leg 21 a and for filament 28 b of leg 21 b.The wire passes through the joint 27 a at the distal end 32 of thestrand of proximal leg portion 26 a, then passes distally to the distalend 23 of the retrieval assembly 15, then proximally to joint 27 b atthe distal end 32 of the strand of proximal leg portion 26 b. In oneembodiment, as illustrated in is FIG. 10C, the filaments are notattached together or to an end cap at distal end 23. In this embodiment,the retrieval assembly 15 resembles an egg whip. Alternatively, an endcap may be used to gather together the filaments at the distal end 23 ofthe retrieval assembly 15 illustrated in FIG. 11.

In yet another embodiment according to the invention, illustrated inFIG. 11, the strands in the proximal leg portion 26 of a retrievalassembly 15 are extensions of twisted or braided strands that form anelongated member 40 or cable. Alternatively, the proximal ends ofstrands in the proximal leg portion are attached to an elongated member40 by any means such as by, for example, insertion in a short cannula,crimping, soldering, welding, swaging, or the use of an adhesive.

In a clinical application in one embodiment, an operator introduces theretrieval device 10 with its distal tip 23 of the retrieval assembly 15in the form shown in FIG. 4A so that the sheath 17 retains the retrievalbasket 15 in its compact form. When the distal tip 23 of the retrievalassembly 15 is positioned proximate calculi or any other material to beretrieved, the operator moves the actuating mechanism 14 from position14 c to the position 14A in FIG. 1. This retracts the sheath 17 andexposes the proximal portion 22 and distal portion 24 of the retrievalassembly 15. The legs 21 return to their original shape as shown in FIG.2 thereby to dilate surrounding tissue and to provide a structure thatcan be manipulated to capture calculi within the confines of theretrieval assembly 15. Preferably, the distal tip 23 of the retrievalassembly 15 is positioned distally of the material to be retrieved priorto displacement of the sheath 17 so that the retrieval assembly 15 isadjacent or distally proximate to the material to ease and speed captureof the material within the retrieval assembly 15.

With the present invention, an operator can manipulate the retrievalassembly 15 so that calculi or other material move in the gap betweenthe filaments in the distal leg portion 28 or between strands in theproximal leg portion 26. The reduced number of strands in the proximalportion 22 of the retrieval assembly 15 greatly facilitates andsimplifies this task.

FIG. 9 depicts an alternative embodiment of a retrieval basket 15 a andsheath 17 a at a distal end 16 a of the retrieval device 10 a. In thisparticular embodiment, the retrieval is assembly 15 a has four legs 21a. Each of the legs 21 a has a proximal portion 26 a in the form of anindividual strand. A distal portion 28 a of each of the legs 21 a hastwo filaments extending from the distal end 32 of the associated one ofthe individual strands in the proximal leg portion 26 a to a cap 25 a todefine a distal portion 24 of the retrieval assembly 15 a. The cap 25 acaptures the ends of all of the filaments in the distal leg portion 28 ato define the distal tip 23 of the retrieval assembly 15 a. In thisparticular embodiment, each of the strands of the proximal leg portion26 a are angularly spaced by about 90° from adjacent strands, while thefilaments of the distal leg portion 28 a are helically wound andangularly spaced by about 45°.

According to the invention, the proximal 22 and distal portions 24 ofthe retrieval assembly 15 are collapsed within the sheath 17 in a firstposition. When the distal portion 24 of the retrieval assembly 15 isextended beyond the end 18 of the sheath 17, the distal portion 24 ofthe retrieval assembly 15 expands into a second position. When both theproximal 22 and distal portions 24 of the retrieval assembly 15 areextended beyond the distal end 18 of the sheath 17 and expanded, theretrieval assembly 15 is in a third position. Positions 1 (one) through3 (three) of the retrieval assembly 15 are positions along a continuumfrom entirely collapsed to entirely expanded retrieval assemblypositions.

The contour of the retrieval assembly 15 of the invention may take avariety of shapes. Referring to FIGS. 12A and 12B, by example, analternate embodiment of a retrieval assembly or basket 15 is shown. Asshown in FIG. 12A, the basket legs 21 of the distal basket portion 24are convex, i.e., the legs 21 are bowed out from the basket center axis.In this embodiment, as the basket moves from the first position to thesecond position, the distal basket portion 24 assumes a bulbous shape.When the basket 15 is extended further from the end 18 of the sheath 17,the proximal basket portion 22 extends from the end of the sheath 17expanding as the basket 15 is moved from the second position to thethird position, illustrated in FIG. 12B. The overall basket contourassumes a peanut shape.

The basket legs 21 of the basket 15 shown in FIGS. 12A and 12B may bepreformed or bent before the basket 15 is assembled. The legs 21 can bebent in any manner known to one skilled in the art, for example, asdetailed in U.S. Pat. No. 5,658,296, the entirety of which isincorporated by reference, herein.

In another embodiment, shown in FIG. 13, the legs 21 of the proximalportion 22 of the basket 15 are substantially straight. As the basket isextended from the distal end 18 of the sheath (not shown), the distalbasket portion 24 expands and the basket assumes a bulbous shape asshown in FIG. 13, second position (inner image). As the basket isextended still further from the distal end of the sheath, the proximalportion 22 of the basket expands. As shown in the third position (outerimage) of FIG. 13, the overall contour of the basket 15 in the thirdposition is cone-shaped. The diameter of the proximal basket portion 22increases uniformly from the proximal end to the distal end of theproximal basket portion 22.

In another embodiment according to the invention, the contour of thedistal basket portion 28 is helical. As illustrated in FIG. 9 forexample, the distal portion 24 of the basket is comprised of a pluralityof spiral-shaped filaments extending from each of the strands of theproximal leg portion 26 of each leg 21. The spiral-shaped filaments 28may be paired. The filaments can be similar to the sets of filamentsdisclosed in U.S. Pat. No. 5,496,330, the entirety of U.S. Pat. No.5,496,330 incorporated by reference, herein. As the distal basketportion 24 is extended beyond the end 18 of the sheath 17, the distalbasket portion 24 expands into a substantially helical shape. The basket20 elongates and expands as the proximal basket portion 22 is extendedfrom the end 18 of the sheath 17 and the basket 20 assumes the thirdbasket position illustrated in FIG. 9.

The use of multiple filaments for the distal portion 28 of a leg 21,increases the number of contact points of the retrieval assembly 15 withany entrapped calculi. In FIG. 9, for example, eight filaments in thedistal basket portion 24 contact the calculi rather than four filaments.Moreover, the close equiangular spacing of adjacent filaments in a givenleg also permits the wires collectively to accommodate any surfaceunevenness of such calculi surfaces to further increase the reliabilitywith which the basket 15 entraps calculi.

FIG. 14 depicts the proximal and distal portions 22 b and 24 b of theretrieval assembly 15 b at the distal end of another embodiment of aretrieval device 10 b. Retraction of the sheath 17 b at the distal endof the retrieval device to the illustrated position enables the proximaland distal portions 22 b and 24 b to form the enlarged retrievalassembly 15 b extending between a cap 25 b and the retrieval assemblybase 30 joined to the elongated member 40 b. Two legs 21 define theretrieval assembly 15 b, with each of the legs comprising an individualstrand 26 b extending distally from the proximal end of the basket andsix filaments 28 b extending proximally from the distal end 23 of thebasket to the distal end 32 of the associated strand 26 b. The filaments28 b in this instance are prestressed to follow a helical path. Thefilaments 28 b are joined to the strands 26 b at joint 27 by any of thejoints illustrated in FIGS. 5A and 5B through FIGS. 8A and 8B.

FIGS. 15-17 illustrate other retrieval device embodiments constructed inaccordance with this invention. The retrieval assemblies 15 c, 15 d and15 e of the retrieval devices 10 c, 10 d and 10 e comprise a pluralityof legs 21 with each of the legs 21 having substantially more filamentsin the distal leg portion 28 of the retrieval assembly 15 than strandsin the proximal leg portion 26. For example, each of the legs 21 c ofthe basket 15 c of FIG. 15 comprises a strand in the proximal legportion 26 c and five filaments in the distal leg portion 28 c, whileeach of the three legs 21 d of the basket 15 d of FIG. 16 comprise astrand in the proximal leg portion 26 d and three filaments in thedistal leg portion 28 d. Four legs 21 d define the retrieval assembly 15e of FIG. 17. Each leg 21 e includes an individual strand in theproximal leg portion 26 e and four filaments in the distal leg portion28 e. Although, each of the filaments of the retrieval assemblies 15 c,15 d and 15 e are prestressed, they are not helically wound like thefilaments of the baskets 15 a and 15 b of FIGS. 9 and 14. For example,in FIG. 17, each of the filaments in the distal leg portion 28 e betweenone of the strands in the proximal leg portion 26 e and the cap 25 e isprestressed to extend radially away from the axis of the retrievalassembly 15 e and to be spaced from each of the other filaments.

The baskets 15 described in connection with FIGS. 2, 9, and 14 through17 may also be formed by the method described in the co-pending,commonly assigned U.S. Pat. No. 5,658,296. Using the process describedtherein provides strands and filaments with improved strength,durability and other characteristics. In another aspect of theinvention, referring to FIG. 18, a retrieval assembly features aplurality of legs 21. The legs 21 comprise a strand that is positionedin the proximal portion 22 of the retrieval assembly 15. The strands ofthe proximal portion 22 of the retrieval assembly are made with rigidmaterials, for example, stainless steel. The distal portion of theretrieval assembly features a flat distal end 23 that is positioned atthe distal end 32 of the strands of the proximal leg portion 26 of theretrieval assembly 15. The distal end 23 comprises a plurality offlexible wires 29 oriented in a plane substantially perpendicular to thelong axis of the retrieval device 10. At least one of the wires 29 atthe distal end 23 is made with a material that is more flexible than thematerial comprising the strands of the proximal basket portion 22. Thewires 29 comprising the distal end 23 of the retrieval assembly 15extend from the distal end 32 of one strand of the proximal basketportion 22 to the distal end 32 of an adjacent strand or to the distalend 32 of another strand of the proximal basket portion 22. The numberof legs or strands in the proximal basket portion 22 may be 3, 5, 6, 7,8 or more and is not limited to the number of strands illustrated.

As illustrated in FIGS. 18B and 18C, in one embodiment of this aspect ofthe invention, the distal end 23 of the retrieval assembly 15 includesat least one wire 29 that extends from the distal end 32 of one strandof the proximal portion of the retrieval assembly 22, to a distal end 32of an adjacent strand, or, alternatively, the at least one wire 29extends across the area defined by the distal ends 32 of the strands tothe distal end 32 of another strand of the proximal leg portion. Anypattern of wires extending from the end 32 of one strand to an end 32 ofanother strand is contemplated by the invention. The wires 29 of thedistal end 23 of the retrieval assembly 15 may form patterns other thanthe patterns illustrated in FIGS. 18B and 18C.

In clinical applications, the device 10 illustrated in FIG. 18A isinserted into a body tract with the retrieval assembly collapsed withinthe sheath 17. When the distal end 18 of the sheath passes by or ispositioned adjacent to the stone or other material to be retrieved. Theretrieval assembly 15 and sheath 17 are moved relative to one another toextend the retrieval assembly 15 beyond the distal end of the sheath 18and open. The gap or distance between basket legs 21 is therebyincreased. The distal end 23 of the basket 15 is maneuverable largelybecause of the flexible material used in making the distal end 23. Theproximal portion 22 of the retrieval assembly is comparatively rigidbecause the proximal portion 22 is made with material more rigid thanthe material used in the distal end 23. Thus, the proximal portion 22has the strength to dilate the body tract around the stone or othermaterial and the distal basket portion 24 has the flexibility to entrapthe stone or other material in the retrieval assembly 15. To capture astone or other material, the stone passes between the gaps in thestrands of the proximal portion 22 of the retrieval assembly 15 and istrapped in the confines between the strands of the proximal portion 22of the retrieval assembly 15 and the distal end 23 of the retrievalassembly 15.

In an alternate embodiment of this aspect of the invention, illustratedin FIGS. 18D-18G, a second elongated guidewire 41 parallels or extendsthrough a lumen in the first guidewire 40, and is joined at its distalend to the distal end 23 of the retrieval assembly 15 and at itsproximal end to a second actuator 42. To capture material 60 in a bodytract, the retrieval assembly 15 is open and extended beyond the distalend of the sheath 17 as illustrated in FIG. 18E. A stone 60 isapproached by the retrieval assembly 15 and trapped between theretrieval assembly 15 and a body tissue 44. As illustrated in FIG. 18F,the second actuator 42 is actuated proximally in the direction of thearrow to axially move the second elongated guidewire 41 proximally. Thedistal end 23 of the retrieval assembly 15 is thereby moved towards thedistal end of the sheath 17, collapsing the retrieval assembly 15 aroundthe stone 60. Actuator 14, illustrated in FIG. 18G, is then movedproximally in the direction of the arrow to draw the retrieval assembly15 with the captured stone 60 partially or entirely into the distal endof the sheath 17.

In another aspect of the invention, in one embodiment, the retrievalassembly 15, illustrated in FIGS. 19A and 19B, has a proximal portion 22and a distal portion 24. The proximal portion 22 of the retrievalassembly has a plurality of legs 21. The distal portion 24 of theretrieval assembly 15 is pocket shaped having an apex 38 and pocketedges 39 that are joined to the ends 32 of the legs 21 of the proximalbasket portion 22. The proximal portion 22 of the retrieval assembly 15is made with a different material than the distal portion 24 of theretrieval assembly.

The legs 21 of the proximal portion 22 of the retrieval assembly aremade with rigid material, such as stainless steel, and are attached attheir proximal end to an elongated member 40, and at their distal end 32to the pocket edges 39 of the pocket in the distal portion 24 of theretrieval assembly. The legs 21 at their distal end 32 are attached tothe pocket edges 39 by sutures, adhesives, loops, hooks or any otherjoining means known to a skilled person.

The pocket-shaped distal portion 24 of the retrieval assembly 15 is anetting or mesh made with a flexible material such as Nitinol. Theopenings in the mesh are large enough to permit fluids to pass but smallenough to impede movement of material, such as stones larger than 0.1mm, through the mesh.

The mesh of the distal portion 24 of the retrieval assembly 15 forms apocket. In one embodiment, the apex 38 of the pocket in the distalportion 24 is positioned at the distal end 23 of the retrieval assembly15. In this embodiment, the retrieval assembly is used to “net” or“sweep” material in a body tract. As illustrated in FIGS. 20A-20C, theretrieval device 10 is inserted into a body tract with the retrievalassembly 15 collapsed within the sheath 17 as illustrated in FIG. 20A.When the distal end 18 of the sheath 17 is advanced past a stone 60 orother material to be removed, the retrieval assembly 15 is extendedbeyond the distal end of the sheath as illustrated in FIG. 20B. With theretrieval assembly 15 positioned beyond the distal end of the sheath,the retrieval assembly 15 is manipulated around the stone 60 to capturethe stone 60 in the pocket formed in the distal portion 24 of theretrieval assembly as illustrated in FIG. 20C.

In another embodiment of this aspect of the invention, illustrated inFIGS. 21A-21 C, the apex 38 of the pocket in the distal portion 24 ofthe retrieval assembly 15 is located proximal to the ends 32 of the legs21 of the proximal portion 22 of the retrieval assembly 15. In thisembodiment, the pocket of the distal portion 24 of the retrievalassembly is used to “scoop” stones or other material in the body tract.The medical retrieval device is inserted into a body tract with theretrieval assembly 15 collapsed within the sheath 17 as illustrated inFIG. 21A. When the distal end 18 of the sheath 17 approaches the stone60 or other material to be removed, the retrieval assembly 15 is movedto the position illustrated in FIG. 21B. With the retrieval assemblypositioned as shown in FIG. 21B, the retrieval assembly 15 is advancedover the stone 60 capturing the stone 60 in the pocket of the distalportion 24 of the retrieval assembly 15 as illustrated in FIG. 21C.

Another embodiment of the invention illustrated in FIGS. 19A-19B,20A-20C, and 21A-21C, is illustrated in FIGS. 22A and 22B. In thisembodiment a second elongated guidewire 41 parallels or passes throughan axially disposed lumen of guidewire 40 (see FIGS. 18D-18G forcomparison) and is attached distally to the mesh of the distal endportion 24 of the retrieval assembly 15. The proximal end of secondguidewire 41 is operatively joined at its proximal end to secondactuator 42 in the manner illustrated in FIG. 18D. Axial movement of theguidewire 41 proximally causes retrieval assembly 15 to move from theeverted position illustrated in FIG. 22A to the inverted positionillustrated in FIG. 22B. Thus, with a first actuator 14 operativelyattached to guidewire 40, and a second actuator 42 operatively attachedto guidewire 41, the medical retrieval assembly 15 of the retrievaldevice 10 illustrated in FIGS. 19A-19B, 20A-20C, 21A-21C can bemaneuvered to capture material in a body tract as illustrated in FIGS.18E-18G and discussed in the corresponding text.

In general, the medical retrieval device according to the invention canbe used in a clinical application to retrieve biological or foreignmaterial from within a body. For example, the device can be used toretrieve a stone (e.g., a stone in the gall bladder, biliary tree,ureter, kidney, urinary bladder, urethra, etc.). The device could alsobe used to capture a thrombus or embolus within a vessel such as thecoronary vessels of the heart or within the pulmonary vasculature.Regardless of the material being retrieved, the device 10 with theretrieval assembly 15 enclosed within a sheath 17 is inserted into abody tract. As the distal end 18 of the sheath approaches a stone 60, orpasses to one side of a stone 60, the retrieval assembly is movedrelative to the sheath 17 and extended beyond the distal end 15 ofsheath 17. The retrieval assembly 15 is maneuvered around the stone 60to capture the stone 60 within the confines of the retrieval assembly 15after the stone 60 passes through the gap between the legs 21 of theretrieval assembly 15. The stone 60 may be approached from the side orfrom the proximal or distal end of the retrieval assembly. The stone 60is captured in the retrieval assembly 15. The stone 60 is removed fromthe body tract by withdrawing the entire medical instrument 10 with theretrieval assembly 15 containing the stone 60, from the body tract.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure andmethodology of the present invention without departing from the scope orspirit of the invention. In view of the foregoing, it is intended thatthe present invention cover modifications and variations of thisinvention provided they fall within the scope of the following claimsand their equivalents.

1-17. (canceled)
 18. A medical instrument, comprising: a proximalhandle; a sheath extending from the handle and including a lumen, thesheath including a distal end away from the handle; and a retrievalassembly that is moveable relative to the sheath to achieve a collapsedposition of the retrieval assembly within the lumen, the retrievalassembly including a proximal portion comprising a plurality of strandshaving a first rigidity and a distal portion comprising at least onewire having a second rigidity, wherein the at least one wire extendsfrom a distal end of one strand to a distal end of another strand. 19.The medical instrument of claim 18, wherein the proximal portion of theretrieval assembly comprises a first material and the distal portion ofthe retrieval assembly comprises a second material different from thefirst material.
 20. The medical instrument of claim 19, wherein thesecond material is more flexible than the first material.
 21. Themedical instrument of claim 18, wherein the distal portion of theretrieval assembly forms a pocket and includes an apex.
 22. The medicalinstrument of claim 21, wherein the apex is positioned at the distal endof the retrieval assembly.
 23. The medical instrument of claim 21,wherein the apex is positioned proximal the distal ends of the strandsof the retrieval assembly.
 24. A medical instrument, comprising: aproximal handle; a sheath extending from the handle and including alumen, the sheath including a distal end away from the handle; and aretrieval assembly that is moveable relative to the sheath to achieve acollapsed position of the retrieval assembly within the lumen, theretrieval assembly including a proximal portion comprising a pluralityof strands, and a distal portion comprising a plurality of filaments,wherein the strands comprise a first material and the filaments comprisea second material different from the first material.
 25. The medicalinstrument of claim 24, further comprising an elongate member, whereinaxial movement of the elongate member in a proximal direction collapsesthe distal portion of the retrieval assembly.
 26. The medical instrumentof claim 25, wherein the elongate member comprises extensions of thestrands that are braided together.
 27. The medical instrument of claim24, wherein moving the sheath in a distal direction causes the retrievalassembly to collapse when it enters the lumen.
 28. The medicalinstrument of claim 24, wherein the first material has a first rigidityand the second material has a second rigidity different from the firstrigidity.
 29. The medical instrument of claim 28, wherein the secondmaterial is more flexible than the first material.
 30. The medicalinstrument of claim 24, wherein the plurality of strands in the proximalportion extend substantially parallel to each other.
 31. The medicalinstrument of claim 24, wherein the plurality of strands in the proximalportion are twisted.
 32. The medical instrument of claim 24, wherein thefilaments are made of a wire.
 33. The medical instrument of claim 32,wherein the wire is used to make two filaments.
 34. The medicalinstrument of claim 32, wherein the wire is used to make threefilaments.
 35. The medical instrument of claim 32, wherein the wire isused to make four filaments.
 36. The medical instrument of claim 24,wherein at least one of the plurality of filaments is joined to at leasttwo strands.
 37. A medical instrument, comprising: a proximal handle; asheath extending from the handle and including a lumen, the sheathincluding a distal end away from the handle; and a retrieval assemblythat is moveable relative to the sheath to achieve a collapsed positionof the retrieval assembly within the lumen, the retrieval assemblycomprising a plurality of legs, at least one of the legs comprising aproximal portion and a distal portion, wherein the proximal portioncomprises a first material having a first rigidity and the distalportion comprises a second material having a second rigidity differentfrom the first rigidity.
 38. The medical instrument of claim 37, whereinthe second material is more flexible than the first material.
 39. Themedical instrument of claim 37, wherein the proximal portion comprises arigid material and the distal portion comprises a flexible material. 40.The medical instrument of claim 37, wherein the proximal portioncomprises a plurality of strands and the distal portion comprises aplurality of wires.
 41. The medical instrument of claim 40, wherein eachof the plurality of strands includes a distal end and each of theplurality of wires is connected to the distal end of at least onestrand.
 42. The medical instrument of claim 40, wherein each of theplurality of strands includes a distal end and at least one of theplurality of wires is connected to the distal ends of two strands. 43.The medical instrument of claim 37, wherein the retrieval assembly ismoveable relative to the sheath to achieve another position of theretrieval assembly in which at least a portion of the retrieval assemblyextends from the distal end of the sheath and assumes athree-dimensional shape out of the lumen of the sheath.
 44. The medicalinstrument of claim 37, further comprising an elongated member thatextends within the lumen from the handle to the retrieval assembly. 45.The medical instrument of claim 37, wherein the distal portion isconnected to the proximal portion by a joint.
 46. A medical instrument,comprising: a proximal handle; a sheath extending from the handle andincluding a lumen, the sheath including a distal end away from thehandle; and a retrieval assembly that is moveable relative to the sheathto achieve a collapsed position of the retrieval assembly within thelumen, the retrieval assembly comprising a plurality of legs, at leastone of the legs comprising a proximal portion having a first rigidityand a distal portion having a second rigidity different from the firstrigidity, and a joint for connecting the proximal and distal portions.47. The medical instrument of claim 46, wherein the joint comprises aloop.
 48. The medical instrument of claim 46, wherein the jointcomprises a hook.
 49. The medical instrument of claim 46, wherein thejoint comprises a crimp.
 50. The medical instrument of claim 46, whereinthe proximal portion of the at least one leg comprises a rigid materialand the distal portion of the at least one leg comprises a flexiblematerial.
 51. The medical instrument of claim 46, wherein the proximalportion of the at least one leg is made of a first material and thedistal portion of the at least one leg is made of a second materialdifferent from the first material.